A case of mucolipidosis Ⅱalpha/beta caused by GNPTAB gene mutation and its enzyme analysis
- 1Department of Pediatrics,The 980th Hospital of the Joint Logistic Support Force of the Chinese People's Liberation Army,Shijiazhuang,Hebei 050083,China
Abstract
Objective To summarize the clinical features,enzymatic and genetic diagnostic approaches in a neonatal case of mucolipidosis(ML)Ⅱα/β caused by compound heterozygous mutations in the N-acetylglucosamine - 1 -phosphatetransferase subunits alpha and beta (GNPTAB)gene,and to elucidate the relationship between its pathophysiology and phenotype. Methods Clinical data of a neonate with ML Ⅱα/β were retrospectively reviewed.Whole-exome sequencing was performed to identify GNPTAB gene variants,and various lysosomal enzymes activities in peripheral blood leukocytes and plasma were measured using fluorogenic substrate assay. Results The neonate exhibited typical manifestations at birth,including distinctive facies,skeletal abnormalities and hypotonia. Genetic analysis identified two nonsense mutations in GNPTAB:c.2404C>T(paternally inherited)and c.289A>T(maternally inherited,de novo). Enzyme activity profiles demonstrated a characteristic with reduced β - galactosidase and β -glucuronidase in leukocytes and markedly elevated total hexosaminidase and β-glucuronidase in plasma. During follow-up,progressive growth retardation,cardiac defects,joint contractures,and neurodevelopmental delay were observed.Conclusion ML Ⅱα/β type is a lysosomal enzyme M6P tagging defect disease caused by GNPTAB gene mutations. It is recommended that β - galactosidase and β - glucuronidase in leukocytes,as well as total hexosaminidase and β -glucuronidase in plasma,be adopted as enzymatic biomarkers for the biochemical testing of MLⅡα/β and MLⅢα/β.Combined enzymatic assay and genetic testing is advised in clinical practice to facilitate early diagnosis and differential diagnosis.
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BibTeX
@article{rujia2026case,
title = {{A case of mucolipidosis Ⅱalpha/beta caused by GNPTAB gene mutation and its enzyme analysis}},
author = {LIANG Rujia and LIU Fang and YIN Xiaowei and DU Zhifang and LIU Jun},
journal = {Zhongguo linchuang yanjiu},
year = {2026},
month = oct,
doi = {10.13429/j.cnki.cjcr.2026.10.025},
url = {https://doi.org/10.13429/j.cnki.cjcr.2026.10.025},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - A case of mucolipidosis Ⅱalpha/beta caused by GNPTAB gene mutation and its enzyme analysis
AU - LIANG Rujia
AU - LIU Fang
AU - YIN Xiaowei
AU - DU Zhifang
AU - LIU Jun
PY - 2026
DA - 2026/10/26
JO - Zhongguo linchuang yanjiu
DO - 10.13429/j.cnki.cjcr.2026.10.025
UR - https://doi.org/10.13429/j.cnki.cjcr.2026.10.025
AB - Objective To summarize the clinical features,enzymatic and genetic diagnostic approaches in a neonatal case of mucolipidosis(ML)Ⅱα/β caused by compound heterozygous mutations in the N-acetylglucosamine - 1 -phosphatetransferase subunits alpha and beta (GNPTAB)gene,and to elucidate the relationship between its pathophysiology and phenotype. Methods Clinical data of a neonate with ML Ⅱα/β were retrospectively reviewed.Whole-exome sequencing was performed to identify GNPTAB gene variants,and various lysosomal enzymes activities in peripheral blood leukocytes and plasma were measured using fluorogenic substrate assay. Results The neonate exhibited typical manifestations at birth,including distinctive facies,skeletal abnormalities and hypotonia. Genetic analysis identified two nonsense mutations in GNPTAB:c.2404C>T(paternally inherited)and c.289A>T(maternally inherited,de novo). Enzyme activity profiles demonstrated a characteristic with reduced β - galactosidase and β -glucuronidase in leukocytes and markedly elevated total hexosaminidase and β-glucuronidase in plasma. During follow-up,progressive growth retardation,cardiac defects,joint contractures,and neurodevelopmental delay were observed.Conclusion ML Ⅱα/β type is a lysosomal enzyme M6P tagging defect disease caused by GNPTAB gene mutations. It is recommended that β - galactosidase and β - glucuronidase in leukocytes,as well as total hexosaminidase and β -glucuronidase in plasma,be adopted as enzymatic biomarkers for the biochemical testing of MLⅡα/β and MLⅢα/β.Combined enzymatic assay and genetic testing is advised in clinical practice to facilitate early diagnosis and differential diagnosis.
SN - 1674-8182
ER -